In fibre optical systems there are at different points required optical connections between the different optical elements included in the system. Thus, there are required optical connections between different lengths of optical fibres, between an optical fibre and a light source, for example a diode, between an optical fibre and a light detector etc. Each connection must be established while using very great accuracy if the losses shall be kept at a minimum. Of course, the problem of providing a correct connection is emphasized by the fact that optical fibres have a very small cross sectional area and that also small deviations from a correct position between two fibre end portions which shall be connected with each other cause substantial losses. It is important especially to avoid angular deviations between the fibres, i.e. it is important that the fibres which are connected with each other are positioned on is the same optical axis.
Different devices for providing a correct connection of optical fibres with each other and with other optical elements have been suggested. Such previously known devices comprise lens systems in which the light beam is magnified so that the light transmission in the connection takes place at a sectional area which is magnified several times providing for a corresponding reduction of the sensitivity to deviations from the correct position. Thereby, it is a drawback that the connection of two fibre end portions to each other requires instead of one single connection, i.e. the connection between the fibre end portions, an optical connection of the fibre end portions to one lens each and an optical connection of the lenses to each other, i.e. three connections. Thereby, it is important that the optical fibres and the lenses are positioned on the same optical axis as well as that the end surfaces of the fibres are positioned in the focus of the lens in question. Thus, the connections between the optical fibres and the lenses constitute the most sensitive parts of the connection system while the optical connection of the lenses to each other can easily be provided without errors.
A previously known device for optical connection of an optical fibre with another optical element, preferably a lens, comprises a substantially sleeve-shaped retainer and a connector element. The sleeve-shaped retainer is intended for fixing the optical fibre in a predetermined position in relation to reference surfaces formed on the retainer and including an end surface of the retainer at which the end surface of the optical fibre is intended to be positioned. The connector element is provided with engagement surfaces adapted to engage the reference surfaces of the retainer for defining the position of the retainer and thereby the optical fibre in relation to the device, the engagement surfaces of the retainer comprising an engagement surface adapted to engage the end surface of the retainer. In addition thereto the connector element has a surface for defining the position of the other optical element, for example the lens, in relation to the end surface of the retainer.